Clinical usefulness of carotid arterial wave intensity in assessing left ventricular systolic and early diastolic performance

Abstract

Wave intensity (WI) is a novel hemodynamic index, which is defined as (d P/d t) x (d U/d t) at any site of the circulation, where d P/d t and d U/d t are the derivatives of blood pressure and velocity with respect to time, respectively. However, the pathophysiological meanings of this index have not been fully elucidated in the clinical setting. Accordingly, we investigated this issue in 64 patients who underwent invasive evaluation of left ventricular (LV) function. WI was obtained at the right carotid artery using a color Doppler system for blood velocity measurement combined with an echo-tracking method for detecting vessel diameter changes. The vessel diameter changes were automatically converted to pressure waveforms by calibrating its peak and minimum values by systolic and diastolic brachial blood pressures. The WI of the patients showed two sharp positive peaks. The first peak was found at the very early phase of LV ejection, while the second peak was observed near end-ejection. The magnitude of the first peak of WI significantly correlated with the maximum rate of LV pressure rise (LV max. d P/d t) (r = 0.74, P << 0.001). The amplitude of the second peak of WI significantly correlated with the time constant of LV relaxation (r = -0.77, P << 0.001). The amplitude of the second peak was significantly greater in patients with the inertia force of late systolic aortic flow than in those without the inertia force (3,080 +/- 1,741 vs 1,890 +/- 1,291 mmHg m s(-3), P << 0.01). These findings demonstrate that the magnitude of the first peak of WI reflects LV contractile performance, and the amplitude of the second peak of WI is determined by LV behavior during the period from late systole to isovolumic relaxation. WI is a noninvasively obtained, clinically useful parameter for the evaluation of LV systolic and early diastolic performance at the same time.

Clinical usefulness of wave intensity analysis

“…Here, clinical measurements have confirmed a similar relation between carotid arterial WI and LV max. dP/dt [26].…”

“…A significant positive correlation is observed. (From [26] with permission) Fig. 4 Relationship between the amplitude of the second peak of carotid arterial wave intensity (W 2 ) and the time constant (s) of LV pressure decay.…”

“…A significant negative correlation is found. (From [26] with permission) intensity, WI b , is practically zero and WI is mainly composed of WI f in the carotid artery. The magnitude of W 1 and W 2 , and the timing of the appearance of their peaks are not affected by backward components.…”

Effects of Thoratec pulsatile ventricular assist device timing on the abdominal aortic wave intensity pattern

“…The first of these two main peaks is shown to represent the contraction of the LV, and the second peak is shown to represent the early diastolic relaxation of the LV. These two peaks might be important parameters to define the circulatory state of a heart failure patient (19,24). The in vitro WI pattern of a PVAD has been shown to be similar to this pattern (13), with a compression wave at the beginning of PVAD ejection and a decompression wave following the deceleration at the end of PVAD ejection.…”

Preload-Adjusted 2 Wave-Intensity Peaks Reflect Simultaneous Assessment of Left Ventricular Contractility and Relaxation

“…[1][2][3][4][5][6] However, the effect of varying degrees of LV volumes (ie, preload) on the use of this parameter has not been characterized. 6 Indeed, when considering maximum values of the derivative of LV pressure (LV dp/dt max) and the LV end-diastolic volume (Ved) relationship, 7 or the elastance and the volumedependent flow changes in the end-ejection period, [8][9][10][11] WI1 may vary with preload. The goal of the present study was to determine whether the use of WI for the analysis of the pressure-volume relationship should be corrected for changes in preload.…”